[PSUBS-MAILIST] BUSBY on Drag /Power Requirement Ratios...

It's either feast or famine! I'm still sitting here bedridden on post-surgery painkillers; got two submarine video projects in the works; the NAUTILUS is in the midst of renovations for an upcoming film-shoot; I just made a new friend over the phone with whom it seems I have the same "roots" in the skydiving and scuba-diving businesses, and it looks like I'm going to acquire his SPORTSUB. What a day!

On top of that, I was just going through MANNED SUBMERSIBLES, and I came across BUSBY's reference to Drag Coefficients and horsepower requirements.

Between pages 392 - 397, BUSBY defines the forces involved, and provides: (1) a chart for computing the Drag Coefficients of Streamlined Bodies; (2) a Nomogram for finding Reynolds Numbers; and (3) a graph for calculating the Effective Horse Power curves for the submarine ALVIN at various velocities.

Busby states the ALBACORE hull design has the most efficient drag coefficients, and gives the Reynolds number for that design. He also gives the drag coefficient number for the ALVIN hull. (The ALBACORE produces roughly 1/10th the drag that ALVIN does.) I haven't actually crunched the numbers yet, but it looks to me like there's enough info here so that, by transposing the ALBACORE Reynolds number in place of that of the ALVIN, I should be able to get a pretty accurate idea of the correlation between EHP and velocity for a streamlined "teardrop spindle-shaped" hull like the ALBACORE.

This appears to be what I've been looking for, since the basis for my high performance minisub is a streamlined steel teardrop hull almost identical in shape to the ALBACORE. (I've got two of them sitting down in the shop right now.)

I think between this information in MANNED SUBMERSIBLES, and the additional documents Mike Holt just sent me, I should be able to come up with a pretty fair guestimation of what the HYPERSUB will do given a particular propulsion source; and maybe even shed some light toward the general quest of a program that will enable this same kind of calculation to be done for other hull shapes, as well.

I've got my SNAPPY video digetizer off line right now while the computer video editing equipment is hooked up; but some time in the future I'll set up to make some JPEG's of the flow-test model for my HYPERSUB, and send them along to Ray so you guys can get an idea of what I'm rambling about.